Re: [PATCH v3 6/7] fscrypt: document inline encryption support

[Eric Biggers <ebiggers@kernel.org>]

On Fri, Jul 17, 2020 at 01:45:39AM +0000, Satya Tangirala wrote:
> Update the fscrypt documentation file for inline encryption support.
> 
> Signed-off-by: Satya Tangirala <satyat@google.com>

Reviewed-by: Eric Biggers <ebiggers@google.com>

> diff --git a/Documentation/filesystems/fscrypt.rst b/Documentation/filesystems/fscrypt.rst
> index f5d8b0303ddf..f3d87a1a0a7f 100644
> --- a/Documentation/filesystems/fscrypt.rst
> +++ b/Documentation/filesystems/fscrypt.rst
> @@ -1204,6 +1204,18 @@ buffer.  Some filesystems, such as UBIFS, already use temporary
>  buffers regardless of encryption.  Other filesystems, such as ext4 and
>  F2FS, have to allocate bounce pages specially for encryption.
>  
> +Fscrypt is also able to use inline encryption hardware instead of the
> +kernel crypto API for en/decryption of file contents.  When possible, and
> +if directed to do so (by specifying the 'inlinecrypt' mount option for
> +an ext4/F2FS filesystem), it adds encryption contexts to bios and
> +uses blk-crypto to perform the en/decryption instead of making use
> +of the above read/write path changes.  Of course, even if directed to make
> +use of inline encryption, fscrypt will only be able to do so if either
> +hardware inline encryption support is available for the selected encryption
> +algorithm or CONFIG_BLK_INLINE_ENCRYPTION_FALLBACK is selected.  If neither
> +is the case, fscrypt will fall back to using the above mentioned read/write
> +path changes for en/decryption.
> +

Nit: most of the text in this file is formatted with textwidth=70.

>  Filename hashing and encoding
>  -----------------------------
>  
> @@ -1250,7 +1262,9 @@ Tests
>  
>  To test fscrypt, use xfstests, which is Linux's de facto standard
>  filesystem test suite.  First, run all the tests in the "encrypt"
> -group on the relevant filesystem(s).  For example, to test ext4 and
> +group on the relevant filesystem(s).  One can also run the tests
> +with the 'inlinecrypt' mount option to test the implementation for
> +inline encryption support.  For example, to test ext4 and
>  f2fs encryption using `kvm-xfstests
>  <https://github.com/tytso/xfstests-bld/blob/master/Documentation/kvm-quickstart.md>`_::
>  
> -- 
> 2.28.0.rc0.105.gf9edc3c819-goog
>